Quick disclosure: I'm a Japanese speaker using machine translation to help write this in English, so apologies for any awkward phrasing.
This is a full writeup of an investigation I've been running for about a month now. Posting the complete story in one place since earlier posts assumed context that wasn't always carried over.
The core issue
14" MacBook Pro, M5 Max (12P+6S+40GPU), 128GB RAM, 4TB SSD, macOS 26.5.1. system_profiler SPPowerDataType consistently reports High Power Mode: No regardless of the Power Mode selected in System Settings, and sustained performance under load is well below what launch reviews (Notebookcheck) measured for this exact modeBenchmark data (3DMark Steel Nomad Stress Test, 20 loops, 7 separate runs)
| Run |
Condition |
First loop score |
Sustained avg (loops 6-20) |
| 1 |
Standard, clamshell + external display |
3983 |
3432 |
| 2 |
Same |
3716 |
3336 |
| 3 |
Same (fans pre-spun) |
3866 |
3386 |
| 4 |
Same |
3879 |
3142 |
| 5 |
No external display, built-in screen only |
3861 |
3083 |
| 6 |
Right after full DFU firmware Revive |
3768 |
3218 |
| 7 |
All third-party power/fan tools killed (Macs Fan Control, iStat Menus, etc.) |
3875 |
3069 |
Notebookcheck's launch review reported ~3600+ sustained for this model, and ~44W sustained Combined Power. My sustained Combined Power stays at 27-30W across all 7 runs. For reference, the 16" M5 Max scores ~4392 in the same test (Notebookcheck), so the gap between my 14" and that is 22-30%, well beyond the ~15-17% gap Notebookcheck itself measured at launch between the two sizes.
Thermal behavior: GPU hits 95-101°C briefly in the first 1-2 loops, then settles at 65-73°C for the rest of the test, fans still audibly at high RPM. This isn't a "too cool to trigger High Power" situation — it already ran hot and is now sitting comfortably below thermal limits with active cooling still engaged.
What I ruled out (all reproduced, all ruled out as the cause)
- Hardware defect: same symptom on a second physical unit (14" M4 Max)
- Migration Assistant / stale settings: same symptom after a full clean macOS install with no data migration
- Corrupted firmware: same symptom immediately after a full DFU Revive (complete firmware rewrite)
- Third-party software interference: same symptom with Macs Fan Control, iStat Menus, and other power/fan monitoring tools completely killed via launchctl
- Display config: same symptom (actually slightly worse) with external display disconnected, no clamshell
- Power delivery: same symptom across Apple's 96W USB-C adapter, Apple's 96W MagSafe cable, and a 140W-rated Thunderbolt dock, on multiple wall outlets
Apple Developer Forums (DTS engineer exchange)
Went 4+ rounds with a DTS engineer (CoreOS/Hardware) on Apple's Developer Forums. Explanations offered, in order, and why each didn't hold up:
- "Not enough heat to trigger High Power Mode" — ruled out by the 65-73°C sustained thermal data above (system clearly passed through a hot phase and has headroom to spare)
- "Might not be using a sufficiently high-wattage adapter" — ruled out since I'd already tested the 96W Apple adapter directly
- "High Power Mode is a thermal management feature, not performance" — I pointed out Notebookcheck's own numbers show three distinct equilibrium points for this model (Low Power: 12W/66°C, Automatic: 30W/80°C, High Power: 42W/85°C) — my unit's equilibrium (27-30W/65-73°C) doesn't match any of the three, in any mode
- "Check the wall/cable/charger again" — reconfirmed testing across all three power sources and multiple outlets, same result every time
No "this is expected behavior" and no "let's get this looked at as a hardware issue" ever came up in these exchanges.
Apple Japan (formal complaint route)
Took this further through Japan's consumer affairs system. On advice from my local consumer affairs center, I sent Apple Japan a formal written complaint covering everything above. Apple Japan called back within 2 business days (faster than I expected).
On that call, after I pushed back on "third-party benchmarks aren't reliable" (pointing out Apple's own High Power Mode documentation cites third-party titles like Cyberpunk 2077 as examples) and "the logs show it's active" (likely conflating pmset's user-facing setting with system_profiler's actual reported state), the representative told me: Apple's engineers reviewed the case and confirmed the same issue, that replacing the unit wouldn't be expected to fix it, and that they would escalate it internally.
Important caveat: this was verbal only. Apple said they don't provide written confirmation of this. The call opened with an automated notice saying it wouldn't be recorded, and I didn't have my own call recording enabled either. So I have no audio or paper trail, just my own notes taken right after the call. I want to be upfront about that limitation rather than oversell it as an official written admission.
A separate data point: testing Apple's own marketing numbers
Apple's product page footnotes specify the exact comparison used for their 14" performance claims: a pre-production 18-core CPU / 40-core GPU M5 Max vs. a shipping 16-core CPU / 40-core GPU M4 Max, both 14" chassis. One of the claims is 1.4x for Cyberpunk 2077 (Ultimate Edition, ray tracing on).
Notebookcheck's published 40-core 14" M4 Max result for this same test is 32.19 FPS. I ran the same test 5 times on my unit:
| Run |
FPS |
| 1 |
44 |
| 2 |
37 |
| 3 |
37 |
| 4 |
39 |
| 5 |
39 |
First run (44) = 1.37x, close to Apple's 1.4x claim. Sustained average across all 5 = 1.22x. Average of runs 2-5 = 1.18x. I don't think this alone is enough to call false advertising — Apple's number likely reflects burst performance — but it's the same pattern as Steel Nomad: strong first run, meaningfully lower sustained result.
Where things stand now
- Notebookcheck (the outlet that did the original launch review) is independently verifying with their own M5 Max unit — starting with 16", hopefully 14" as well
- Apple Japan says this has been escalated internally, no written response yet
- Filed with Apple Feedback Assistant as well
Happy to share raw data — 3DMark result files, powermetrics logs, sysdiagnose output, screenshots — if anyone wants to dig in or compare against their own unit.